This invention relates to aircraft protection, and more particularly, to a charge control system to reduce the risk of a lightning strike on an aircraft.
On average, a civil air is struck by lightning at least once per year. The probability of an aircraft being struck while airborne is much higher than that of a stationary aircraft on a runway. Part of the reason is that the aircraft modifies the electric fields in the vicinity which acts as a catalyst for lightning inception and attachment. Specifically, an aircraft located in an electric field becomes polarized and the local electric field values at the aircraft surface are magnified at the extremities where the radius of curvature of the conducting structure is smaller, such as on wing tips, stabilizer tips aircraft nose, etc. The foregoing applies to both fully metallic aircraft and aircraft with a substantial past of their structural material made of composites so long as copper mesh or expanded foil is embedded in the structural material to ensure high electrical conductivity. This electric field enhancement can result in the development of a bi-directional leader extending from opposite polarity aircraft extremities, which may eventually connect with oppositely charged regions in a cloud or ground. Through this process, the aircraft triggers a lightning strike with itself being in the direct path of the return stroke current flowing between the attachment locations. See, FIG. 1 that shows the sequential limitation of a positive leader followed by a negative leader in a sufficiently high electric field.
It is an object of the present invention to provide a system for minimizing the likelihood that leaders will form that can result in a lightning strike.